This invention refers to a method for displaying spheroidal products which are carried on a conveyor chain made up of a set of pairs of supporting pads, so that each two pairs of supporting pads carry a single product: this method consists in providing a controlled rotation of the product by inverting the rotation direction of at least one of the supporting pads which carries the item along its route, so that the entire surface can be visible in a short path by means of a camera placed in an overhead position, for example. The invention also refers to a machine for implementing this method.
More specifically, the products to which the invention refers are fruit, and more specifically citrus fruit, such as oranges and mandarins.
Food products, and particularly citrus fruit, are marketed through the corresponding brands. The consumer of a brand trusts in its quality, and the marketing company needs to provide the means required for this quality to be maintained over time. One of the causes for rejecting citrus fruit is what is known as “rot”, but normally due to Phytophthora genus fungi.
Fruit and vegetable processing plants handle a large number of the products to be treated. A processing line of a fruit and vegetable processing plant for processing and packing citrus fruit comprises several items, such as the preliminary sorting table, selectors, calibrators or sizers, conveyor belts, etc.
One of the items forming the processing lines for citrus fruit is what are known as “discotheques” in which the blemishes caused by the fungi are visible under ultraviolet light.
The action of ultraviolet light is nevertheless harmful for people and even when the selection of healthy fruit has generally been done manually up to the present time, it is desirable for the process to be carried out automatically.
There are automatic devices in which the products are made to rotate regularly, and the surface of the citrus fruit is observed by means of a set of cameras arranged on at least two side of the travel direction. This requires processing at least two sequences of images for each fruit, which proves expensive and slow.
The invention being proposed allows the entire surface area of the fruit to be displayed, and this can be observed by a single camera, in the mass-processing sequence at fruit and vegetable processing plants, so that its quality can be properly monitored for its distribution, packing and later marketing.
Hence, the purpose as a whole of this invention is to provide fruit and vegetable processing plants with an effective automatic system for eliminating rot (fruit infested by fungi which must as a priority be removed from other sound fruit in the post-harvest stage, as this affects the fruit around it by contact). It also allows the early detection of fruit with fly bites, undetectable to the human eye, and the detection of fruit that is still unripe, which enables automatic degreening in the early season, as well as other types of common defects such as blemishes, scars, branch damage, roundness and shape defects, wateriness, texture, etc.
Given that new legal norms are extremely strict as regards people's exposure to the effect of ultraviolet radiation (sorting by manual selection of rotten fruit is done at fruit and vegetable packing plants in closed areas, here commonly known as “discotheques” where blemishes are visually detected by fluorescent tubes with ultraviolet lighting.) Sorters are exposed to this ultraviolet light for the whole season, with the corresponding health and legal risks. Other automatic selection devices are extremely costly and the effectiveness of their results has not been sufficiently proven. Current regulations demand the minimum exposure and/or the suppression of these procedures.
The automatic selection system proposed is located in a selection unit to be integrated in the plant after the general sorting stage, in the place where “discotheques” are currently located and intended to replace these, before the application of waxes, but after prior selecting, washing and drying of fruit for proper visualisation with the least possible dirt.
The aim is thus to replace the current manual separation booths for separation of fruit with rot (“discotheques”) located after the manual selection tables, with the system proposed, which would enable the selection and removal of fruit with common defects and rot and bites invisible to the human eye, and also possible selection and colour discrimination, which would allow degreening in the early season. This represents an extraordinary improvement for installations with mechanical calibration, as this can easily be adapted, without having to make large investments in reintroduction of this machinery.